/Engine/Source/Runtime/Media/Public/IMediaBinarySample.h
Get the GUID identifying the derived type that may implement additional, type specific methods. If the GUID matches a type known type it is safe to static cast this class to the derived type. This is usually done to identify the format of the binary data carried here.
virtual [FGuid](API\Runtime\Core\Misc\FGuid) GetGUID() const